| The root swelling disease of stem mustard is seriously harmful,resulting in a serious impact on its yield and quality.Due to the very limited control methods,the application of nanotechnology to control the disease has gradually become a new means.Nanomaterials have physical and chemical properties such as large specific surface area and small size effects,making them excellent in antibacterial properties.In this paper,the effect and mechanism of nano magnesium oxide(MgO NPs)on the prevention and control of stem nodule mustard root nodule disease were studied,and the effects of MgO NPs on soil physicochemical properties,soil enzyme activity,and soil bacterial community structure,as well as on the defense enzyme activity and salicylic acid content of stem nodule mustard were explored.In this paper,a new idea of using MgO NPs to control stem mustard root swelling disease is proposed,which also provides a theoretical basis for the research on the mechanism of nano materials to control crop diseases.The main research results of this paper are as follows:(1)MgO NPs were screened from eight kinds of nanomaterials,which had a good control effect on stem tumor mustard root swelling disease.After treatment with MgO NPs,the incidence of stem tumor mustard root swelling disease was reduced,and the incidence rate and disease index were 57.63% and 21.25,respectively,significantly lower than the water control group,but significantly higher than the F-1000 control group.Using different concentration gradients of MgO NPs(500,1500,and 2500 mg/L)to treat stem mustard,it was found that there was no significant correlation between the control effect of MgO NPs on root nodule disease and the treatment concentration.After treatment with MgO NPs,the aboveground growth of stem mustard plants significantly increased,with stem diameter,effective leaf number,leaf length,leaf width,and maximum leaf area significantly higher than those of the water control group.(2)The results showed that different concentrations of MgO NPs had different effects on the physicochemical properties of soil around the root of stem mustard.The treatment of 500 mg/L MgO NPs significantly increased soil p H;The treatments of 500 mg/L and2500 mg/L of MgO NPs significantly reduced soil alkaline hydrolysable nitrogen;There were no significant differences in available potassium,electrical conductivity,magnesium,and water control between groups treated with different concentrations of MgO NPs,but the exchangeable magnesium and water-soluble magnesium in the 500 mg/L MgO NPs treatment group were significantly higher than those in water,F-1000,and 2500 mg/L nano treatments,respectively.(3)The results showed that the activities of soil peroxidase(POD),soil alkaline protease(AP),soil alkaline phosphatase(ALP),soil urease(Urease),and soil sucrase(Sucrase)in the MgO NPs treatment group were significantly higher than those in the water control group,and with the increase of the concentration,the enzyme activity also increased,but were significantly lower than the F-1000 control group,Soil catalase(CAT)showed an opposite trend.(4)The effect of different concentrations of MgO NPs on the bacterial community structure in the rhizosphere soil of stem mustard showed that compared with water control group and F-1000 treatment,MgO NPs treatment could significantly increase the bacterial community structure in the rhizosphere of stem mustardαDiversity.There were significant differences in the composition of bacterial phyla,genus,and species in the rhizosphere of stem mustard under different treatments.With the increase of MgO NPs treatment concentration,the relative abundance of Bacteroidetes decreased significantly,with the lowest proportion at a concentration of 2500 mg/m L.However,after treatment with low concentrations of MgO NPs,the relative abundance of some rhizosphere bacteria that promote plant growth significantly increased,such as Pseudomonas and Agrobacterium.(5)The results showed that the activities of superoxide dismutase(SOD)and catalase(CAT)in stem mustard treated with MgO NPs at different concentrations were significantly lower than those in the water control group,and the activities of 2500 mg/L treatment were the lowest,which were 41.86% and 29.29% lower than those in the water control group,respectively,but both were significantly higher than those in the F-1000 control group;The activities of peroxidase(POD),phenylalanine ammonia lyase(PAL),polyphenol oxidase(PPO),guaiacol peroxidase(POX),and salicylic acid(SA)in stem mustard treated with MgO NPs were significantly higher than those in the water control group,and the enzyme activity also increased with the increase of concentration.When MgO NPs was 2500 mg/L,the activity was the highest,which was 55.56%,103.40%,55.95%,82.59%,and 95.17% higher than that in the water control group,respectively,But both were significantly lower than the F-1000 control group. |
